Shwertmannite has been known to have a high arsenic adsorbing property. Shwertmannite is an iron oxide hydroxide sulfate salt having a composition of Fe8O8(OH)8-2x(SO4)x (1≦x≦1.75), and the shwertmannite that has adsorbed arsenic is stabilized in structure and continues to retain arsenic. Known literatures referring to the arsenic adsorption of shwertmannite include non-patent literatures 1-5, and those referring to the cleaning of water polluted with arsenic by shwertmannite include a non-patent literature 6.
Non-patent literature 1: Anion adsorbing mechanism of shwertmannite (Keisuke Fukushi, Tsutomu Sato and Nobuyuki Yanagise, Preprint of 2001 Meeting of the Clay Science Society of Japan, 45, p. 78-79);
Non-patent literature 2: Adsorption of arsenic (IV) by shwertmannite (Keisuke Fukushi, Yoshikazu Sakaki and Tsutomu Sato, Preprint of 2001 Meeting of The Mineralogical Society of Japan, 2000, p. 71);
Non-patent literature 3: Process of modification of low crystalline iron mineral and behavior of arsenic (Keisuke Fukushi, Yuki Kotake, Tsutomu Sato and Nobuyuki Yanagise, Preprint of 2001 Meeting of Mineralogical Society of Japan/Symposium of The Japanese Association of Mineralogists, Petrologists & Economic Geologists, 2001, p. 106);
Non-patent literature 4: Natural arsenic cleaning in Nishinomaki discontinued mining area in Gunma prefecture (Keisuke Fukushi, Yoshikazu Sasaki, Tsutomu Sato, Nobuyuki Yangihara and Hikaru Amano, Preprint of 2001 Meeting of Atomic Energy Society of Japan);
Non-patent literature 5: Natural arsenic cleaning in Higashi-Daira prior mining area in Gunma prefecture (Keisuke Fukushi, Yoshikazu Sasaki and Tsutomu Sato, Preprint of 2000 Meeting of The Clay Science Society of Japan, 44, p. 52-53);
Non-patent literature 6: Cleaning of arsenic-polluted well water with shwertmannite in Bangladesh (Tsutomu Sato, Keisuke Fukushi, Ken-ichi Ito, Hotaka Ikeda, Kazuhiro Hamabe and Baku Yokota, Preprint of 2002 Meeting of The Mineralogical Society of Japan, 2002, p. 47).